Learning
Objectives
Upon
successful completion of this module you will be able to:
-
Define the term surfactant and explain its role in the pulmonary
system.
-
Explain the composition and function of pulmonary surfactant.
-
Identify and differentiate between types of exogenous surfactant
preparations.
-
Describe the clinical effects, complications, and hazards of exogenous
surfactant therapy.
Introduction
In
the 1920s the importance of surface tension in pulmonary physiology
was first realized. However, it was not until the 1950s that surfactant
was first described, when it was found that material obtained from
alveolar washes could significantly reduce surface tension on dynamic
film compression. Soon after these early reports, it was speculated
that a deficiency of pulmonary surfactant may play an important
role in the pathophysiology of various pulmonary conditions. Following
these reports there has been an explosion of information on surfactant
composition, metabolism, biophysical, and physiological activity.
This has led to a better understanding of surfactant deficient and
dysfunctional disease states, and the potential therapeutic benefits
of surfactant replacement therapy.
The major role of surfactant is to allow large variations in surface
tension during lung expansion and deflation. This action promotes
alveolar stability, reduces atelectasis, decreases edema formation
and minimizes the work of respiration. These physiological functions
are dependent on the biophysical properties of surfactant which
include: rapid adsorption to the air-liquid interface, respreadability
after compression, and the ability to alter surface tension during
dynamic compression and expansion.
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